python-sounddevice: sounddevice.PortAudioError: Error opening InputStream: Device unavailable [PaErrorCode -9985]

When trying to record, I use the line

myrecording = sd.rec(duration * fs, samplerate=fs, channels=2,dtype='float64')

This leads to

> Traceback (most recent call last):
  File "sd_test.py", line 7, in <module>
    myrecording = sd.rec(duration * fs, samplerate=fs, channels=2,dtype='float64')
  File "C:\Users\gwerner004\AppData\Local\Programs\Python\Python36\lib\site-packages\sounddevice.py", line 224, in rec
    ctx.input_dtype, callback, blocking, **kwargs)
  File "C:\Users\gwerner004\AppData\Local\Programs\Python\Python36\lib\site-packages\sounddevice.py", line 2417, in start_stream
    **kwargs)
  File "C:\Users\gwerner004\AppData\Local\Programs\Python\Python36\lib\site-packages\sounddevice.py", line 1301, in __init__
    **_remove_self(locals()))
  File "C:\Users\gwerner004\AppData\Local\Programs\Python\Python36\lib\site-packages\sounddevice.py", line 780, in __init__
    'Error opening {0}'.format(self.__class__.__name__))
  File "C:\Users\gwerner004\AppData\Local\Programs\Python\Python36\lib\site-packages\sounddevice.py", line 2572, in _check
    raise PortAudioError(errormsg, err)
sounddevice.PortAudioError: Error opening InputStream: Device unavailable [PaErrorCode -9985]

When I do python -m sounddevice I get this line:

>  1 Microphone (Plantronics C320), MME (2 in, 0 out)

Why would this device not be available for recording?